The present invention generally relates to a thermal printing material, and more particularly to a thermal printing material which can provide a highly reliable printed image, the reliabilities of the printed image involving a light resistance, a water resistance, a heat resistance and a chemical resistance.
The research and development of thermal printing materials becomes active so as to meet the progress of information processing technology and the increasing needs of the market. This is because the thermal printing materials have advantageous features: that is, (1) a process of heating the thermal printing material can easily realize an image printing; (2) an image printing apparatus using the thermal printing material can be easily built in a simple and compact form; and (3) the thermal printing materials are inexpensive and easy to use.
The technology of thermal printing materials is applied in various manners to information processing, medical measurement electronics, facsimile communications, copiers and printers, point-of-sales systems, and the like. The recent demands in these fields for a thermal printing material to provide a more reliable recorded image are increasing.
In order to improve the image printing reliabilities of heat sensitive materials, various kinds of developers for use in the heat sensitive materials have been proposed by the following prior art:
p-toluensulfonilhydrazide PA1 hydroxynaphthoic acid derivatives PA1 1,4-bis(.beta.-2,4-dihydroxybenzoyloxyethoxycarbonyl)benzene PA1 salicylic acid derivatives
(Japanese Laid-Open Patent Application No.62-294590)
(Japanese Laid-Open Patent Application No.63-28691)
(Japanese Laid-Open Patent Application No.63-72590)
(Japanese Laid-Open Patent Application No.1-168486)
However, any of the conventional thermal printing materials mentioned above have not had image printing reliabilities sufficiently high to meet the recent demands. The heat resistance, light resistance, water resistance, and chemical resistance of the conventional thermal printing materials have been insufficient.